Figure 5

From focusing zone plate to diffracting aperture or darkness. Interaction of (a) identical and (b) inverted Fresnel zone plate patterns A and B on the metasurface beam splitter. When the transmitted lens pattern A and the reflected lens pattern B are in phase (φ=0), identical zone plates yield a bright focal spot, while inverse zone plates add up to a diffracting circular aperture. When the zone plate patterns are out-of-phase (φ=π), identical zone plates block all light, while inverted zone plates focus. For clarity, measured and simulated light propagation are shown on a reduced intensity scale for the effective aperture and absorber cases. Column 1 shows the projection of zone plate A onto the metasurface at z=0 when blocking beam path B. Column 2 shows the projection of zone plate B while blocking path A. For simultaneous illumination of both zone plates, columns 3 and 4 show measured and column 5 shows simulated intensity distributions for different propagation distances z. All color scales show intensity. See Supplementary Figs. S4 and S5 for detailed results on inverted zone plate patterns.